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Hi, I am trying to send data from one controller to another directly ie without converting it into serial. Now when i send the data using 232 it is being received alright and the out put is also displayed. i am using putchar and getchar. but when i try this by directly connecting the Tx of first controller to Rx of next the data is either not being read properly or not being transfered properly. I'm just not getting what is going wrong. it should work i think i have even made the ground common for both the controllers.
Thanks Ajay.
Just Trying to avoid redesigning , is it possible to avoid redesigning and still have data transmitted using 232 ? Of course it is. HOWEVER you are running TWO risks a) a '51 port to the outside is ve.. nah, extremely noise senitive b) a '51 port to the outside is the most likely of any chip pin to blow when exposed to EMI
THUS, you can not design the above, however, you can, of course "make" it.
In our company there are "inspirational posters" hanging all over the place and one has the phrase "sign your work with quality", if you do the port pin to the outside world you will "sign your work with hope"
Erik
Hi erik,
So Basically i should redesign.
Thanks. Ajay
If the two boards are connected using a fixed connector, and connected together in a factory then you might decide to run raw TTL signals between the chips.
If the two chips are using a cable (longer than of a couple of cm) and not in a shielded box, then you should definitely consider hardware protection for the pins. Using RS-232 signals is one of the easiest ways to at least partially protect your hardware and at the same time reduce the noise sensitivity.
If this is a hobby project, the above may not matter. If it is commercial product, you are more or less forced to productify the circuit and choose solutions where all sensitive hw have protection from daamge, all communication has enough noise protection and error detection/correction, and all hf signals are properly blocked by EMI filters so that the equipment can be submitted for emission testing.
Hi, The Project that i'm working on is just for experiment right now but hoping that it would be of some commercial use later on. i'll make sure i use some kind of protection as every one is saying that and most probably skip the TTL idea in favor of 232. Thanks Ajay
May I push this issue one direction.
One always should make a best effort for making the proper design with quality.
You will have enought bugs to sort without going itsi bitsi. If you make with quality, you know there is no problem.
We develop circuits and things that are sold - that is what I do - and we do not know how far these products are going to go. Do not take your chances. Maybe it is an electric pan that you are making, maybe is a garage door remote controller or a printer sharing box. All should be made with quality. You never know how important the failure may get.
Make it proper. Make it with pride.
Your sequence of postings show that you have not decided yet where you are going. I believe you are proud enought to make it proper. So put the max 232 in your board.
RE-design? No problem, after all, it will take you 30 minutes to make the max 232 circuit work.
You have only few boards to make the modification? No problem. Costs of max 232 are low.
You will have a comercial product? No problem, mas 232 will make comms reliable.
When you are seasoned enought, with a product that is mature, you will be able to cut the costs and still make it with quality.
Ed.